Manufacture of paper



Patented July 7, 1931 ,UNITED STATES HAROLD ROBERT BAFTON', PROCESS CORPORATION, A CORPORATION OF MASSACHUSETTS mUrAcrU RE or PAPER No Drawing.

This invention relates to the manufacture of paper, and more particularlv to paper filled with alkaline filler.

The principal object of this invention is to provide a novel method for the employment of casein bearing constituent in paper made with alkaline filler.

An important object is to provide a novel method of using broke in paper made with alkaline filler. p A

A further object is to provide a method of using coated broke whereby the coated broke will give a minimum of trouble from lump formation in the stock.

A further object is; to provide a'method for improving paper machine operation and preventing breakson the paper machine.

Other objects and advantages of this invention will become ap arent during. the course of the following description.

In my copending application Serial No. 325,406, filed December'11,-1928, I make the disclosure that in the manufacture of paper filled with alkaline filler, the presence of a constitutent bearing a flotation agent, particularly one of a nitrogenous nature, especially casein, results at times in the formation of soft lumps in a papermaking furnish made with' alkaline filler, particularly in the case in which the fibrous material includes old paper stock. The principal source of such casein in .the furnish is normally the adhesive present in the coating of the waste or imperfect coated paper known as coated broke (this term including the coated'paper present in clippings, trim mings, or the like) which finds its way normally into the beater furnish in a paper mill with which a coating, mill is conjointly operated. Of course, casein may also have its source in waste coated paper purchased from outside sources for use as an ingredientof the, fibrous mix.

In y 00 ending applications Serial N05,! 'ditional water usually being added. The

$25,407 an 325,408, both filed December 11, 1928, I disclose methods by which paper machine operation may-be improved when casein bearing constituent is an ingredient of the paper mix containing alkaline filler,

, particularly where old paper stock is pres- PATENT OFFICE MASSACHUSETTS, ASSIGNOR 'ro BAFFOLD Application filed March 17, 1930. Serial No. 436,651.

ent in the furnish. The method disclosed in Serial No. 325,407 is that of adding I 7 acidic material to the mix under conditions favoring the minimizing of the time and/or intimacy of contact of the constitutents of the mix, i. e. at the wet end of the paper machine; the method disclosed in Serial No. 325,408 is that of adding the alkaline filler, or both acidic material and. alkaline filler, to the mix under similar conditions, -i. e. at the ./wet end of the paper machine.

I have now discovered another method of accomplishing the same result which in certain instances, particularly where there is to be a relatively high percentage of coated broke used in the furnish, seems to have certain advantages over the methods referred to above. .My method is to add the coated broke to the fibrous mix under'conditions favoring the -minimizing.of the time and/or or the like, together with the other fibrous constituents, and to incorporate therewith such other material as may be employed in papermaking such as filler, size, for example rosin size, size precipitant, for example alum, tinting and the like. This mix usually has a dry solid content of approximately 5 per cent. more or less. The mix after being subjected to suflicient treatmentin the beater is then ordinarily discharged into a container commonly called a beater chest, ad-

mix may be transferred from the beater chest to a suitable refining engine, usually a .jordan, at a dry solid content which may be in the neighborhood of approximately 4- per cent. In common practice the mix is at this point usually diluted, somewhat by the mix after jordaning is ordinarily conducted from the jordan to another container commonly known asa machine chest. From the machine chest the .is transferred to a point near the web forming end of the paper machine where it is largely diluted with water, this point being normally, referred to as the mixing box, water being here added in such an amount as to provide a dry content of approximately 0.5 to l per cent. or slightlyhigher, but usually not in excess of 1.5 per cent, The mix in such highl dilute condition is then passed through r' ers or the like if desired, and thereafter through screens and through the headbox of the paper machine on to the machine wire, or into a vat, depending upon whether a Fourdrinier or a cglinder machine is employed; and during t 's passage additional amounts of water are usually added inthe form of sprays or otherwise.

This exact procedure is not always followed but in some instances is modified in accordance with the type of paper being made. For example, in the manufacture of certain t pes of paper the heating process is almosti not entirely dispensed with, the ingredients being merely mixed together prior to jordaning. In some instances the step of refining or j ordaning may be partially if not wholly dispensed wlth. Moreover in some cases the arrangement of steps is different, for example, the jordan may be placed subsequent to the machine chest, the stock passing directly from the jordan to the mixing box. Sometimes also the arrangement of the chests or the numberof the chests used is varied. In general, however, it can be stated that inthe p'apermaking process, regardless of the variations which may occur, the ingredients are normally mixed and/or treate in a relatively concentrated condition, and maintained therein for a substantiallength of time, and then the mix is subsequently largely diluted preparatory to delivery to the web-forming device, and it refor a relatively brie the coated broke is added in the beater.

80 coated broke a substantial amount of .the

mains in this highlfy dilute condition only period of time.

Under normal operation as outlined above,

Sometimes the coated broke is processed, usually in contact with water, prior to addition tothe beater in order to defibre it or at least break it up, and sometimes an attempt is made to remove as b washing the ingredients of the coating. guch attempts at removal by washing, however, are in most cases inadequate to remove the entire coating, and hence even with so=cal1ed washed original casein present usually accompanies the disintegrated coated broke into the eater.

In the manufacture of either sized or unv bepractically ception of the. coated broke.

sized paper, when coated broke is added to a fibrous mix in the beater in which ordinary inert inorganic filler such as clay is used, and in which the beater mix is normally acidified as with alum, the casein is insolubilized, precipitated, or rendered inactive by this acidification and gives comparatively particularly true when old paper stock is an ingredient of the furnish.

I have discovered that this activation of the casein takes place to a considerable extent only when a substantial time of contact is allowed between-the casein bearing constituent and the alkaline filler. The activa-* tion is especially fostered when the mix containing these two ingredients remains for some time in concentrated condition, and particularly when it is subject in such concentrated conditionto agitation such as it would normally receive in the chests ,for example. I have also discoveredt hat the disadvantages inherent in the method hitherto employed of utilizing coated broke in alkaline filler furnishes can be overcome to a very great extent by minimizing the time and/or intimacy of contact of the coated broke with the other constituents of the fibrous 'mix, particularly the alkaline constituent, i. e. the alkalinefiller, and I have devised a method whereby my discovery can utilized in the papermaking operation.

In the practice of my invention I add to the beater or other compounding or mixing machine the fibrous materials with the ex- The I, alkaline filleris also added in the beater, except in the instance where I wish to practice the present invention in conjunction with that disclosed in my copending application Serial No. 325,408, in WhlCll case I add the alkaline filler at the wet end of the paper machine. However, even in. such. case some alkaline filler usually finds its Wa into the beater with the machine broke. may also add size and/or alum in the beater if desired. Then the mix is subjected to the usual treatment up to the point where it is ready to be delivered from the final chest, which is usually the machine chest.

To the fibrous mix so prepared I add coatprocess, for example, subsequent-to the passage of the mix from the machine chest and preferably at the west end of the paper machine, whereby the time of contact of the casein of the coated broke with the other constituents of the mix is greatly minimized.

If the coated broke-be added, as is pref- A erable, in the dilute stage of the papermaking process, such addition acts to decrease greatly the intimacy of contact of the coated broke with the other constituents of the mix. Thus my invention consists broadlyin adding the coated broke to the fibrous mix under conditions favoring the minimizing of the time and/or intimacy of contact between it and the other constituents of the mix.

It will thus be apparent that my method of utilizing coated broke in the papermaking furnish prevents to a considerable extent the solubilizing or activating influences formerly inherent in the method of adding coated broke to alkaline filler furnishes in the beater. The removal of the coated broke from the earlier part .of the papermaking operation also acts to eliminate' this source of putrescence from part of the system.

ln certain cases, such as where therefining engine is placed between the final stock chest and the paper machine, the coated broke may be added to the mix just subsequent to delivery of the mix from this final chest and it thus passes through the refining engineyusually a jordan. In this case the earlier the jordan acts as an eflicient incorporating -means for the coated broke in the paper mix and also of course acts to refine the fibrous constituents thereof, in the customary manner. The coated broke should of course as described below be disintegrated before this jordaning. Inasmuch as the time of contact in the concentrated condition is only .very brief, the results are in certain cases satisfactory. However, in most cases I have found it preferable to effect the mixing of the coated broke with the remainder of the fibrous constituents at the wet end of the paper machine, usually at the mixing box or at any point which may be convement prior to delivery of the mix to the web-forming device.

Of course in order to add coated broke at the wet end of the paper machine it is necessary that it should .be 'defibred prior to this addition. A suitable way is to treat it in a separate disintegrator such as a broke heater or the like. The coated broke after distintegration may be given a refining treatment as in water suspension by a jordan engine or the like and then conducted to the wet end ofthe paper machine where it is added to the fibrous mix preferably when the mix is being diluted at the mixing box. The addition of thecoated broke is made preferably continuously and preferably in constant proportion .to the fibrous mix which is being introduced into the mixing box. It is possible, especially in the case of thoroughly disintegrated coated broke, to feed the disintegrated coated broke, providing it has been disintegrated to the point where'it will break up readily in dllute aqueous suspension, in relatively,

concentrated semi-solid form, into the mixing box, but this method of procedure is or inarily not so advantageous as the. one described just above.

If the coated broke is added just prior to j ordaning in certain cases as indicated above where the jordan delivers to the mixing box of the paper machine, previous ordaning of the coated' broke of course will be unnecessary in such cases.

The casein of the coated broke may be substantially insolubilized of precipitated, suitably after disintegration of the coated broke and prior to its introduction into the paper mix, by any known casein insolubilizing or precipitating agent. This serves to substantially deactivate the casein so that it will not be in a condition to cause trouble in the paper mix. Aldehyde such as formaldehyde may be employed, or acidic material such as sulphuric acid, or alum, or other compounds of aluminum, or acidic metallic salts such as zinc chloride or the like, or even neutral metallic salts, although I have not found the latter to be so efficacious. Such chemical pretreatment of the coated. broke prior to its, addition to the fibrous mix is especially advantageous in the case where the coated broke contains substantially no alkaline filler. The pretreatment can also be employed in the case where the coated broke contains alkaline filler, but in such case non-acid insolubiliz ing agents should be used, or if acidic agents be used the quantity of alkaline filler present should be taken into consideration in calculating theamount of acidic material required for acidification.

In ordinary paper machine operation, the machine broke, i. e. the broke from the paper machine, is fed directly, or after disintegration, to the beater; this returns casein bearing stock to the beater: Also, particu larly in those cases where settling or filtration cycles on the excess .white water return the material recovered from theexcess white water to the earlier stage of the process, either to the beater as is sometimes done in settling systems, or' to the chests as is sometimes done in filtration systems, it will be apparent that part of the casein from the coated broke in the furnish will be returned to an earlier stage in the process. This, as has been indicated above, is not theoretically the most advantageous procedure. However, owing to the fact that the larger part of the casein is incorporated into'the sheet as it passes over the web-forming device, only a minor percentage of the insoluble casein will be returned to an earlier stage in 3 stage. j

My inventlon may be conveniently eming, sodium silicate,

the process through recovery systems; and inasmuch as the addition of the coated broke at a late stage in the process prevents to a very material degree the solubilizing ofthe casein, naturally only a relatively small quantity of casein-in solubilized form will be carried by the excess white water and thus be introduced at an earlier stage 'in the pro cess. Also, the proportion of casein returned to the beater in the machine broke is relatively minor. As the quantity of casein reintroduced at an early stage in the process is thus small compared with the original amount of casein introduced into the furnish, no serious detriment will be incurred from the presence of this minor quantity of casein in that part of the system prior to the passage of the mix from the machine chest, especially if the casein-containing material recovered from the white waters be reintro-' duced as is preferably in the later partof the system, such as in-the machine chest. However, if it is feasible, it is especially advantageous in this connection to employ the machine cycle disclosed in my copending. application Serial N 0. 438,644, filed March 24, 1930, whereby substantially all the recoveredmaterial is returned to the papermaking operation just prior to or at the dilute ployed in the manufacture of either sized or substantially unsized papers. It may be car- "ried out as indicated above in connection 3 with the processes disclosed in 'my two copending applications Serial Nos. 325,407 and 325,408 mentioned above, or in connection with processes disclosed in various of my other copending applications,- that is, coated 40 broke may be the only material'added at the wet end of the paper machine, or one or more of the following materials may also be added at this point: alkaline filler, acidic material such as alum, size, precipitated sizrecipitated sodium sillcate, starch or the l' e.

'As will be apparent to one familiar with the papermaking art, the amount of coated broke added to a furnish may be varied with in wide limits depending upon the type of paper to be made as -well as on the amount of coated broke which is available for or must be utilized in the papermaking process. I therefore do not limit myself to any definite proportion of the coated broke to be'used'in relation to the other constituents of the furnish. J

Where I use the expression soft lumps I mean lumps which have their origin sub-- sequent to the screening of the stock, being formed in the headbox, inlet or the like. These lumps are entirely different, and easily distinguishable by practical papermakers, from slime, i. e. masses of stocklusually fermented or decomposed which settle or form on chest and pipe surfaces, and when dislodged work through the screens and on tothe wire. Of course, slime also forms in the head-box and inlet after the machine has run for a relatively long period of time .without wash-up, but the soft'lumps I describe are entirely distinct therefrom and form, and start to give trouble, even within as short a time as several hours after the headbox and inlet have been thoroughly cleaned. Where I use the word casein herein, I use it in the generic sense to include casein and/or compounds or derivativesthereof.

By the'term alkaline filler I mean substantially water insoluble filler which when agitated in contact with freshly boiled distilled water, say for an hour, will impart a pH value to such water greater than 7.0, that is, which will be on the alkaline side of the neutral point. Among fillers in -cluded in this group may be mentioned calcium carbonate,'of which lime mud from the causti'cizing process is one form; calcium carbonate magnesium basic carbonate employed in the paper disclosed in my U. S. Patent N 0. 1,595,416, dated August 10,1926; calcium carbonate magnesium hydroxide disclosed in my U. S. Patent No. 1,415,391, dated May 9, 1922; and other substantially water insoluble normal or basic carbonates of alkaline earth metals (which expression is herein intended. to include magnesium), or compounds, double salts, or physically associated mixtures "of these with one or more other acid soluble materials of a substantially water insoluble nature.

By the termfalkaline filler I also intend to incllide fibrous material or the like containing one or more compounds of the character referred to, such as old papers or similar papers, broke, or the like.

When I use the word *paper? herein, I use it in the broad sense to include roducts of manufacture of all types and weights and thicknesses, which contain as an e$ential constituent a considerable While I have described in detail the pre-, ferred embodiment of my invention, it is to be understood that the details of proof all and an;

formation such as the mixing box, regulat- A cedure, the proportions of ingredients, and

the arrangement of steps may be widely varied without departing from the spirit of my invention or the scope of the subjoined claims.

I claim:

1. The steps in the method ofmanufacturing paper filled with alkaline filler comprising addingflotation agent bearing material to, a fibrous mix under conditions favoring the minimizing of the time of contact'of said material with the constituents of the mix, and thereafter making paper therefrom.

2. The steps in the method of manufacturing paper filled with alkaline filler comprising adding flotation agent bearing ma- 'terial to a fibrous mix under conditions favoring the minimizing of the time and in timacy of contact of said material with the constituents of the mix, and thereafter making paper therefrom.

3. The steps in the method of manufac= turing paper filled with alkaline .filler comprising adding casein-bearing material to :1 fibrous mix under conditions favoring the minimizing of the time of contact of said material with the constitutents of the mix, and thereafter making paper therefrom.

4. The steps in the method of manufacturing paper filled." with alkaline filler comprising adding coated broke to a fibrous mix under conditions favoring the minimizing of the time of contact of the coated broke with the constituents of the mix, and thereafter making paper therefrom.

5. The step in a method of manufacturing paper filled with alkaline filler comprising adding coated broke to a fibrous mix subsequent to the passage of the mix from the machine chest.

6. The step in a method of manufacturing paper filled with alkaline filler comprising adding coated broke to a fibrous mix at the wet end of the paper machine.

7 The step'sin the method of manufacturing paper filled with alkaline filler comprising adding flotationagent bearing material, in which the flotation agent has been sub,, stantially insolubilized, to a fibrous mix under conditions favoring the minimizing of the time of contact of said material with the constituents of the mix, and thereafter making paper therefrom.

8. The steps in the method of manufacturing paper filled with alkaline filler comprising adding flotation agent bearing material, to which acidic material has been added, to a fibrous mix under conditions favorlngthe minimizing of the time of contact of said material with the constituents of the mix, and thereafter making paper there: from.

9. The steps in the-method of manufacturing paper filled with alkaline filler comprising. adding flotation agent bearing material, to which acidic metallic compound has been added, to a fibrous mix under conditions favoring the minlmizing of the time of contact of said material with the constituents of the mix, and thereafter making paper therefrom.

10. The steps in the method of manufacturing paper filled with alkaline filler'comprising adding flotation agent bearing material, to which aluminum compound has has been added, to a fibrous mix under conditions favoring the minimizing of the time of contactof said material with the constit-- uents of the mix, per therefrom.

11. The steps in the method of manufacturing paper filled with alkaline filler comprising adding flotation agent bearing mater1al, to which alum has been added, to

a fibrous mix under conditions favoring" the-minimizing of the time of contact of said material with theconstituents of themix, and thereafter making paper therefrom.

12. The steps in the method of manufacturing paper filled with alkaline filler com prising adding coated broke, to which alum has been added, to a fibrous mix under conditions favoring the minimizing of the time of contact of the coated broke with the constituents of the mix, and thereafter making paper therefrom.

13. The step in amethod of manufacturing paper filled with alkaline filler comprising adding acidified coated broketo afibrous mixat the wet end of the paper machine.

14. The step in a method of manufactur ing paper filled with alkaline filler comprising adding coated broke previously treated with alum to a fibrous mix of the paper machine.

15. The steps in a method of manufacturing paper filled with alkaline fillercomprising adding coated brokeand alum to a fibrous mix at the wet end of the paper machine. A

' 16. The steps in a method ofmanufacturing paper filled with alkaline filler comprising adding coated broke, alkaline filler, and alum to a fibrous mix at the wet end of the paper machine.

17. The steps in a method of manufacturing paper filled with alkaline filler comprising adding coated broke, alkaline filler,-size, and alum to a fibrous mm at the wet end of the paper machine.

18. The steps in. a method of manufacturat the wet and and thereafter making paing paper filled with alkaline filler comprlsingadding coated broke, alkaline filler,

size, starch, and alum to a fibrous mix at the wet end of the paper machine.

19. The step in a method of manufacturing paper filled with alkaline filler com- 20. The method of manufacturing paperfilled with alkaline filler comprising mixing alkaline filler and fibrous ingredients with the exception of coated broke in the heater,

5 and adding coated broke subsequent to thepassa e of the mix from the machine chest; and tiereafter making paper therefrom. 21. The-method of manufacturing paper filled with alkaline filler comprising mixing p in the beater alkaline filler and fibrous ingredients with the exception of coated broke, adding coated broke at the wet end of the 1 paper machine, and thereafter making paper therefrom. w v 15 In testimony whereof I aflix my signature.

. HAROLD ROBERT RAFTON. 

